Selective heating system for automatic washing machine

ABSTRACT

A dishwasher having upper and lower utensil support racks and a heater element positioned adjacent each rack for preselective drying of utensils held in the racks. Manually operated selector switches are provided in electrical series with the dishwasher timer control circuit for determining which of the heaters will be operative during the washing and drying cycle.

United States Patent Jacobs 1 Jan. 18, 1972 [541 SELECTIVE HEATINGSYSTEM FOR 3,271,878 9/1966 Martin ..34/48 X AUTOMATIC WASHING MACHINE3,186,417 6/1965 Fay ..l34/108 X 3,329,529 7 1967 L 4 5 [72] Inventor:James W. Jacobs, Dayton, Ohio 13 l 8 D X [73] Assignee: General MotorsCorporation, Detroit, FOREIGN PATENTS OR APPLICATIONS Mich- 233,50310/1963 Austria ..134/ss D [22] Filed: May 19, 1970 PrimaryExaminerRobert L. Bleutge pp 38,750 Attamey-William s. Pettigrew,Frederick M. Ritchie and Edward P. Barthel [52] U.S.Cl. ..l34/58 D,34/48, 134/107,

200/38 B, 219/189, 219/492, 307/141.8 [571 ABSTRACT A dishwasher havingupper and lower utensil support racks 0 re and a heater elementpositioned ad acent each rack for 34/4548 200/38 219/492 307/1418preselective drying of utensils held in the racks. Manually operatedselector switches are provided in electrical series [56] Reerences Citedwith the dishwasher tirner control circuit for determining UNITED STATESPATENTS which of the heaters will be operative during the washing anddrying cycle. 3,186,418 6/1965 Stern ..134/58 D 3,064,662 1 l/ 1962Given et al ..134/108 X 3 Claims, 2 Drawing Figures SELECTIVE HEATINGSYSTEM FOR AUTOMATIC WASHING MACHINE This invention relates todishwashers and more particularly to a selective heating arrangement foranautomatic domestic dishwasher.

With the development of the dishwashing art, it has been an objective toprovide for special loads such as fine china and delicate crystal inorder to make the operation of the appliance more flexible. Forinstance, the operator may desire to dry dishes in one of a selectivenumber of racks and to avoid overheating and possible damage to finechina held in other racks.

Accordingly it is an object of this invention to provide a dishwasherwith means for selective drying of utensils whereby special loads suchas fine china may be washed in certain unheated racks to obviate thedanger of their being overheated to cause damage thereto.

A further object of this invention is to provide a control circuit forprogramming the washing and drying cycle of an automatic dishwasherincluding means to preselect which of a plurality of heaters, each ofwhich being located in heat transfer relation with an associated utensilsupporting rack, is energized during the cycle.

Further objects and advantages of the present invention will be apparentfrom the following description, wherein a preferred embodiment of thepresent invention is clearly shown.

In the drawings:

FIG. 1 is a generally schematic representation of a dishwasherincorporating the invention;

FIG. 2 is a schematic wiring diagram for controlling the dishwasher inaccordance with the teachings of this invention.

In accordance with this invention and with reference to FIG. '1, adishwater is shown composed of a casing 12 enclosing a dishwashingchamber 14. The dishwashing chamber 14 is closed at the front thereof bya dishwater door (not shown) and having at the bottom thereof adepressed sump 16 leading to a water distribution system of the typetaught in the commonly assigned US. Pat. No. 3,265,311 issued Aug. 9,1966, the disclosure thereof being incorporated herein by reference.

The water distribution system of the dishwasher 10 may include a pumpassembly 18 driven by the motor 20. The pump assembly 18 includes arotatable spray arm 21 thereon to which fluid is supplied from the sumpregion 16 for distribution through the dishwashing chamber 14 during acleaning cycle of the dishwasher as established by a sequence or timercontrol means 22 having a timer control knob 23 located on the front ofan upper panel.

In general, the water distribution system includes the revolving sprayarm 21 located beneath a lower utensil support rack 24 and a rotatingspray column or tube 26 affixed to said spray arm and extending upwardlythrough a guard portion 28 of the lower rack permitting the removal ofthe lower rack from the dishwashing chamber. The spray tube 26 is formedwith an enlarged or bulbous housing portion 30 at the top thereof havingan outlet 32 aimed through an open passageway 34 formed by a centralwire network on an upper utensil support rack 36. The jet stream fromthe outlet 32 may be aimed at a rotatable and freely rotating swirlspray impeller or wabble plate water deflector 38 above the upper rack36. The details of one such system is shown in US. Pat. No. 3,292,645issued Dec. 20, 1966 and assigned to the assignee of the presentinvention and the disclosure thereof is incorporated herein byreference. The reversible motor 20 directly drives the axial flow pump18 in one direction in accordance with the teachings of theaforementioned US. Pat. No. 3,265,31 l to recirculate the water forwashing or rinsing, and when reversed pumps the water to drain.

An annular lower heater element 40 is located below rack '24 and can beperiodically energized throughout the operating cycle to providerecovery heat to the wash and rinse water and for supplying heat to theutensils in the rack 24 during the drying cycle. The lower heater 40 isretained in the cabinet by suitable securing means such as looselymounted metal clip members generally indicated at 42 which are bolted orotherwise affixed to the side of the cabinet and allow for expansion ofthe heater. An upper annular heater element 44 is positioned immediatelybelow the upper rack 36 for eating the utensils therein in a manner tobe described. The upper heater 44 is preferably supported so as to bepartially encased by an underlying annular troughshaped wire-mesh guardstructure indicated at 46 suitably supported from the cabinet forguarding the heater 44 against contact by an operator using the lowerrack or otherwise inadvertently reaching into the lower portion of thechamber. Again suitable clips 48 and 49 may be used to secure the heaterguard 46 and the heater 44 to the cabinet structure. While the heaterelements can be of various wattages the preferred embodimentcontemplates each heater 40, 44 having equal outputs of approximately500 watts when energized with a 1 15 volts 60 cycle AC power supply. Asuitable blower fan (not shown) may be employed with an outside grilleto blow moisture laden air from the dishwashing chamber 14 during thedrying cycle as described in the US. Pat. No. 3,292,645.

The upper rack 36 may be used for cups, glasses, bowls, saucers, etc.,while the lower rack 24 is adapted for receiving plates, bowls, servingdishes, pots and pans, and a silverware basket (not shown). The racksare made of heavy gauge steel wire which is coated with suitableresilient material such as white vinyl plastic. Each rack has nylonrollers indicated at 50 and 52 to allow easy movement of the racks 24and 36 respectively, in and out of the dishwashing chamber duringloading and unloading thereof. The nylon rollers 50, 52 glide onstainless steel glides, such as 54 for the lower rack and 56 for theupper rack, which are screw fastened to the sidewall of the washingchamber in a suitable manner. As an alternate, glides may be embossedinto the sidewalls of the chamber.

As shown in FIG. 2, power from a l 15 volt power supply L,, 1. isprovided for energizing the components of the control circuitry. Inorder to prevent operation of the dishwasher 10 with the door open, adoor switch 57 is included. The sequentially operated circuitry of thedishwasher 10 is controlled by the timer 22 having a timer motor 60which is selectively energized by a line switch 61 wherever the timercontrol knob 23 is depressed or pushed inwardly. The timing motor 60 isadapted to intermittently rotate a cam shaft 64 to selectively andsequentially open and close a plurality of cam-actuated switches. Asolenoid-actuated fill valve 66 is selectively energized through acam-actuated switch blade 68 to open and close the contact A forenergizing a valve (not shown). The heating elements 40 and 44 areenergized from heating element contacts B and C which are opened andclosed by heater switch blades 74 and 76 actuated by the cams on theshafi 64. The push-pull switch 61 is located on one end of the axiallyshiftable timer shaft 80 and is closed whenever the timer motor 60 isactuated to control a dishwashing cycle.

The motor 20 includes a main run winding 82, a water distributing startwinding 84 and a water draining start winding 86. A current responsivestart relay 88 serves to energize the appropriate start winding inaccordance with the timer selection of contacts D or E for a briefperiod until the motor comes up to its designed running speed and thecurrent flow in the main winding drops off. Bypass switch 90 isoperative through contacts F, G to return the timer push-pull knob 23 toits outward stop position after a full washing and drying cycle.

As mentioned above, one of the primary objects of this invention is toprovide an improved heating means to achieve preselective drying withoutoverheating of utensils such as fine china. In accordance with thisobject, there is provided a manually operated preselector switch 91having individual manually operated switches 92 and 94 (FIG. 2).Switches 92, 94 are controlled by pushbuttons 96, 98 respectively, asseen on the control panel in FIG. 1. Referring again to FIG. 2, it canbe seen that if switch 92 is closed, the operation of switch 74 will beeffective to operate the heating element 40. In other words if switch 92is closed the overall operation of the heater will be controlled by thetimer switch 74. Similarly, if switch 94 is closed, the operation of theheater element 44 is dependent upon the timer cams which control theoperation of switch 76. It is to be understood that the pushbuttonswitches 96, 98 are of the independent type whereby the depression orrelease of one has no effect on the remaining pushbutton.

Referring now to H0. 2 the following selection of operations can beachieved. If it is desired to have a complete regular cycle of thedishwasher, neither pushbuttons 96 and 98 are depressed therebymaintaining switches,92 and 94 in their nonnally closed positions.Control knob 23 is rotated slightly to a preindicated position and thendepressed, whereby switch 61 is closed to energize timer motor 60. Fromthis point on, timer motor 60 will drive the sequence control meansthroughout an entire cycle. The heater elements 40 and 44 will beenergized for a portion of the wash to maintain the water temperature atthe desired level while during the dry period both the heaters 40, 44will be continuously energized.

To achieve a less intense drying action for such articles as fine chinain the upper rack 36, pushbutton 98 is depressed thereby opening switch94. With switch 94 open, the operator rotates knob 23 slightly and thendepresses it until switch 61 is closed by its cam thereby energizingtimer motor 60 which again will drive the sequence control means throughan entire cycle. Since switch 94 is open electrical power is notprovided to the upper heater element 44 but only to the lower heaterelement 40.

The result is a preselectable drying cycle in which only the utensils inthe lower rack are subjected to intense radiant dry- I ing heat whilethe special load such as fine china in the upper rack is protectedagainst overheating. Because the heater elements have approximatelyequal wattage outputs that are substantially less than a conventionalsingle-heater element dishwasher the invention insures that the finechina in the upper rack will not be damaged by heat from the energizedlower heater element 40.

Another option open to the operator involves depressing pushbutton 96which opens switch 92 whereby the same operation is achieved asdescribed above the depressing pushbutton 98 except the energization ofthe heater elements is reversed with upper element 44 being energizedrather than lower element 40. This option could be employed to washlarger pieces of fine china or the like in the lower rack to insureagainst possible overheating.

It has been determined that for fine china the drying temperature shouldnot exceed approximately 190 F. to insure that the glazed coating on thechina will not develop fine cracks in the coating otherwise known aschecking." By virtue of using individual low output heater elements theinvention achieves a radiant heat drying arrangement wherein the radiantheat imparted to the racks does not exceed this critical temperature of190 F. in normal operation when both heaters 40 and 44 are energized. Itshould be noted that in the instant arrangement the heaters are eachspaced in a horizontal plane located a distance of the order of 1%inches below the bottom of their associated racks 24 and 36respectively, providing an arrangement wherein this maximum temperatureof 190 F. is not exceeded.

Still another option is open to the operator by depressing bothpushbutton switches 96 and 98 thereby opening both switches 92 and 94during a presoak or rinse and hold operation wherein a partial load ofdishes is rinsed but the machine is not operated at a full-washing cycleuntil a full load of dishes are in the machine. It is of coursepossible, if desired, to operate the dishwasher for a full cycle withoutthe energization of either heater 40 or 44.

While the embodiment of the present invention as herein describedconstitutes the preferred form, it is to be understood that other formsmight be adapted.

What is claimed is as follows:

1. A dishwasher comprising, a casing defining a washing chamber having asump and an access opening; a plurality of utensil supporting rack meanssecured to said dishwasher casing; heating means located adjacent eachof said rack means; each said heating means comprising an annular heaterelement located in underlying relation respectively to each of saidplurality of utensil supporting rack means; said heater elements eachhaving substantially equal wattage outputs whereby said utensilsupporting rack means are uniformly heated; a fill valve in fluid supplyrelationship to said chamber and said sump; pump means for distributingwashing fluid against utensils in said rack means to be cleaned and fordraining fluid from said chamber; power means for said pump means; acontrol circuit for said dishwasher including separate means forenergizing and deenergizing each of said heating means, said fill valveand said power means; timer means for sequentially actuating saidenergizing and deenergizing means in a dishwashing cycle includingperiods of fill, wash, rinse and dry; manually operated preselectablemeans in electrical series circuit with certain of said timer actuatedmeans for energizing and deenergizing said heating means wherebyactuation of said manually operated preselectable means will detenninewhich of said heating means will be operative during the dishwashingcycle.

2. A dishwasher comprising, a casing defining a washing chamber having asump and an access opening; upper and lower utensil supporting rackssecured to said dishwasher casing; heating means located adjacent eachof said racks; said heating means comprising upper and lower annularheater elements having substantially equal power outputs, said upper andlower heater elements spaced below said upper and lower utensilsupporting racks respectively at a distance sufficiently close theretoto exert a radiant heat drying effect upon the utensils therein suchthat the radiant heat imparted to the utensils does not exceedapproximately F.; a fill valve in fluid supply relationship to saidchamber and said sump; pump means for distributing washing fluid againstutensils in said rack means to be cleaned and for draining fluid fromsaid chamber; power means for said pump means; a control circuit forsaid dishwasher including separate means for energizing and deenergizingeach of said heating means, said fill valve and said power means; timermeans for sequentially actuating said energizing and deenergizing meansin a dishwashing cycle including periods of fill, wash, rinse and dry;manually operated preselectable means in electrical series circuit withcertain of said timer actuated means for energizing and deenergizingeach of said heater elements whereby actuation of said manually operatedpreselectable means will determine which of said heater elements will beoperative during the dishwashing cycle.

3. An automatic dishwasher comprising, a casing defining a washingchamber having a sump and an access opening; upper and lower rackssecured to said dishwasher casing in the upper and lower portions ofsaid casing; said upper and lower racks for supporting utensils to bewashed and dried; upper and lower annular heating elements havingsubstantially equal power outputs of approximately 500 watts at USvolts; said upper and lower heater elements spaced approximately 1%inches below their associated upper and lower racks thereby providing aradiant heat drying effect upon the utensils in each said rack whichdoes not exceed approximately 190 F.; a fill valve in fluid supplyrelationship to said chamber and said sump; pump means for distributingwashing fluid against the utensils to be cleaned and for draining fluidfrom said chamber; power means for said pump means; a control circuitfor said dishwasher for sequentially controlling a dishwashing cycleincluding periods of fill, wash, rinse and dry; said control circuitincluding a timer motor, a group of cams operated by said timer motor; agroup of switches operated by said cams for energizing and deenergizingsaid upper heater element, said lower heater element, said fill valve,and said power means; and a preselectable manually operated selectorswitch in electrical series with each of said timer-operated heaterelement switches whereby actuation of said manually operated selectorswitches will determine which of said timer motor operated heaterelement switches will be in operative relationship with the remainingtimer motor operated switches during the dishwashing cycle.

1. A dishwasher comprising, a casing defining a washing chamber having asump and an access opening; a plurality of utensil supporting rack meanssecured to said dishwasher casing; heating means located adjacent eachof said rack means; each said heating means comprising an annular heaterelement located in underlying relation respectively to each of saidplurality of utensil supporting rack means; said heater elements eachhaving substantially equal wattage outputs whereby said utensilsupporting rack means are uniformly heated; a fill valve in fluid supplyrelationship to said chamber and said sump; pump means for distributingwashing fluid against utensils in said rack means to be cleaned and fordraining fluid from said chamber; power means for said pump means; acontrol circuit for said dishwasher including separate means forenergizing and deenergizing each of said heating means, said fill valveand said power means; timer means for sequentially actuating saidenergizing and deenergizing means in a dishwashing cycle includingperiods of fill, wash, rinse and dry; manually operated preselectablemeans in electrical series circuit with certain of said timer actuatedmeans for energizing and deenergizing said heating means wherebyactuation of said manually operated preselectable means will determinewhich of said heating means will be operative during the dishwashingcycle.
 2. A dishwasher comprising, a casing defining a washing chamberhaving a sump and an access opening; upper and lower utensil supportingracks secured to said dishwasher casing; heating means located adjacenteach of said racks; said heating means comprising upper and lowerannular heater elements having substantially equal power outputs, saidupper and lower heater elements spaced below said upper and lowerutensil supporting racks respectively at a distance sufficiently closethereto to exert a radiant heat drying effect upon the utensils thereinsuch that the radiant heat imparted to the utensils does not exceedapproximately 190* F.; a fill valve in fluid supply relationship to saidchamber and said sump; pump means for distributing washing fluid againstutensils in said rack means to be cleaned and for draining fluid fromsaid chamber; power means for said pump means; a control circuit forsaid dishwasher including separate means for energizing and deenergizingeach of said heating means, said fill valve and said power means; timermeans for sequentially actuating said energizing and deenergizing meansin a dishwashing cycle including periods of fill, wash, rinse and dry;manually operated preselectable means in electrical series circuit withcertain of said timer actuated means for energizing and deenergizingeach of said heater elements whereby actuation of said manually operatedpreselectable means will determine which of said heater elements will beoperative during the dishwashing cycle.
 3. An automatic dishwashercomprising, a casing defining a washing chamber having a sump and anaccess opening; upper and lower racks secured to said dishwasher casingin the upper and lower portions of said casing; said upper and lowerracks for supporting utensils to be washed and dried; upper and lowerannular heating elements having substantially equal power outputs ofapproximately 500 watts at 115 volts; said upper and lower heaterelements spaced approximately 1 1/2 inches below their associated upperand lower racks thereby providing a radiant heat drying effect upon theutensils in each said rack which does not exceed approximately 190* F.;a fill valve in fluid supply relationship to said chamber and said sump;pump means for distributing washing fluid against the utensils to becleaned and for draining fluid from said chamber; power means for saidpump means; a control circuit for said dishwasher for sequentiallycontrolling a dishwashing cycle including periods of fill, wash, rinseand dry; said control circuit including a timer motor, a group of camsoperated by said timer motor; a group of switches operated by said camsfor energizing and deenergizing said upper heater element, said lowerheater element, said fill valve, and said power means; and apreselectable manually operated selector switch in electrical serieswith each of said timer-operated heater element switches wherebyactuation of said manually operated selector switches will determinewhich of said timer motor operated heater element switches will be inoperative relationship with the remaining timer motor operated switchesduring the dishwashing cycle.